1. Field of the Invention
The invention relates to oscillators and more specifically to voltage controlled microwave oscillators.
2. Description of the Prior Art
Typically, prior voltage controlled oscillators operating at X-band and higher have been implemented using Gunn diodes and resonant cavities. These circuits had the disadvantage that they were relatively complex to build due to the inherent complexity of constructing resonant cavities at X-band (7-12 GHz) frequencies. Additionally, these circuits tended to have moderate post tuning drift characteristics. The high junction temperatures of the Gunn diodes reduced the reliability of the circuits. A need exists for high frequency oscillators (7-12 GHz which exhibit the desirous features of low post tuning drift, low noise rapid frequency changing capability and extremely linear frequency versus voltage characteristics. In the prior art, attempts have been made to meet these needs by using a low frequency oscillator followed by a frequency multi-plier. This resulted in circuits which were expensive, difficult to tune and an output signal high in harmonic content.